(1) Field of the Invention
The present invention relates to a high-energy fuel, and more specifically it relates to a liquid fuel having a high density and a high calorific value which is used in rockets or jet engines.
(2) Description of the Prior Art
In a rocket and a jet engine for a turbo jet, a ram jet, a pulse jet or the like, a high-energy liquid fuel is used. In order to increase thrust of the jet engine, there is required a fuel having a greater combustion energy per unit weight, i.e., a liquid fuel having a high density and a great combustion heat. The liquid fuel for rockets and jet engines is fed through a pipe to a fuel chamber, but since a flying object loaded with the rocket or the jet engine flies at a high altitude and because of being used together with liquid oxygen, the liquid fuel is exposed to an extremely low temperature. Therefore, other requirements which are necessary for the liquid fuel for jet engines are that the freezing point and pour point are low and that a suitable viscosity is retained even at a low temperature. Further, it is also required that the liquid fuel for rockets and jet engines has no unsaturated bonds and is stable during long-term storage.
As such liquid fuels for rockets and jet engines, there are heretofore known exotetrahydrodicyclopentadiene (JP-10, Japanese Patent Publication No. 20977/1970) obtained by isomerizing a hydrogenated dicyclopentadiene with an acid catalyst and a dimerized and then hydrogenated norbornadiene (RJ-5, U.S. Pat. No. 3,377,398). However, JP-10 is good in low-temperature fluidity but has the drawbacks that density is low and that combustion heat per unit volume is small. On the other hand, RJ-5 has a great combustion heat per unit volume, but it is poor in low-temperature fluidity, is difficult to synthesize, and is expensive, inconveniently.